The American war cemetery, center, at Colleville sur Mer, overlooks Omaha Beach on May 6 in Normandy, France. The cemetery contains the remains of 9,387 American troops who died during the June 6, 1944, invasion of Nazi-occupied France. Skybox Imaging via AFP/Getty Images

Allied troops land at Gold Beach on June 6, 1944, in France. British Ministry of Defense via epa

Aerial view of the Allied ships off the landing beaches of Normandy on June 13, 1944. AP

U.S. Army soldiers conduct a landing operation on D-Day at Omaha Beach. British Ministry of Defense via epa

A British Royal Air Force Mustang aircraft from II Squadron flies over France during D-Day. The aircraft from the squadron were used to photograph the landing beaches to update commanders on the progress of the assault. British Ministry of Defense via epa

The landings in Normandy begin. British Ministry of Defense via epa

People view the gun battery installation at Pointe du Hoc on April 8 near Caen in Normandy. The Germans had fortified the area with concrete bunkers and gun emplacements. On D-Day, U.S. forces scaled the cliffs and seized the area. David Vincent, AP

People walk past remains of a German bunker at Pointe du Hoc. David Vincent, AP

The American war cemetery at Colleville sur Mer overlooks Omaha Beach. David Vincent, AP

Sword Beach, left, and Juno Beach near Caen, Normandy, were the landing areas for the British 3rd Infantry Division. David Vincent, AP

An aerial view of Pegasus Bridge near Ouistreham, Normandy. The 6th British Airborne Division captured the bridge before dawn on D-Day. David Vincent, AP

The wreckage of the Arromanches Harbor rests at Gold Beach in Arromanches, Normandy, France. The portable temporary harbor was developed by the British to create a protected area to unload thousands of tons of supplies onto the beaches during the Allied invasion. David Vincent, AP

The concrete bunkers of the German Longues-sur-Mer battery remain in a field in Normandy. The Longues-sur-Mer artillery battery was part of Germany's Atlantic Wall coastal fortifications. David Vincent, AP

The American War cemetery of Colleville sur Mer is pictured on April 8, in Normandy, France. The cemetery overlooks Omaha Beach, one of the landing beaches of the Normandy Invasion, and contains the remains of 9,387 American military dead, most of whom were killed during the invasion of Normandy and ensuing military operations in World War II. France is preparing to mark the 70th anniversary of the D-Day invasion which took place on June 6, 1944. David Vincent, AP